Well intervention, completion and drilling equipment are used to feed pipe into and out of subterranean wells. As an example, snubbing units are known in the oil and gas industry for facilitating access to a well which is under pressure. A snubbing unit manipulates various tubular components such as pipe, tubing, and bottomhole assemblies into and out of a well while controlling the well under pressure. A conventional snubbing unit includes stationary and traveling slips which are operated sequentially to shift tubulars into and out of the well through a wellhead, despite the possibility of heavy tubular loads which urge the tubulars to fall into the well (“pipe heavy”), or the reservoir pressure-generated forces on the tubulars, which urge the tubular out of the well (“pipe light”).
While snubbing into or out of the well, a transition or “balance point” occurs between pipe light and pipe heavy, where the pipe weight and the lift force exerted by the well acting on the cross-sectional area of the pipe string is substantially equal. Subsequently, hundreds of feet of pipe can be moved with minimal effort.
Snubbing is conventionally controlled manually by an operator, who activates the traveling and stationary slips in sequence when snubbing into or out of a well. The snubbing slips are load bearing components and rely on friction to restrain the tubulars or pipe string. However, it is not uncommon for an operator to release one set of load bearing components accidentally, before transferring the load to the other set of load bearing components. Such an error may result in the pipe string being dropped or ejected, placing personnel at risk and damaging equipment.
Therefore, there is a need in the art for a method and system which mitigates the difficulties of the prior art.